A variety of studies on the clinical disorders of male reproduction are in progress. These include 1) studies of the hormonal regulation of spermatogenesis in hypogonadotropic men, 2) the effect of high venous ligation in fertile men with varicocele, 3) analysis of several biochemical parameters of sperm metabolism in men with necrospermia and 4) longitudinal evaluation of the adverse effects of cytotoxic drugs on testicular function in men receiving chemotherapy for malignant disorders.